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Basic faults and diagnosis of steering. Steering diagnostics and maintenance Steering diagnostic tools

General information

General diagnostics

The steering wheel is difficult to turn

– Hydraulic system – use a pressure gauge to check the pressure in the system.

– Jammed or stuck steering gear.

Excessive ease when turning the steering wheel

– Wheel bearings are worn or loose.

– The steering gear is loose.

– The connections between the steering column and the steering gear are loose or worn.

– The adjustment of the steering gear preload is broken.

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The steering wheel does not return well to its original position

– There is insufficient lubrication in the ball joints and tie rod ends.

– Jamming of ball joints.

– Jamming in the steering column.

– The front wheels are out of alignment.

– The adjustment of the steering gear preload is broken.

– Valve jamming.

– The clutch on the steering gear is set too low.

50 l

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0 1 2 3 4 5 6 7 8 9 From prin (machines).

MP.190.604.048.011
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Selection of equipment for the maintenance and repair area.
Name Overall dimensions (m.) Brand Number of
Tool cabinet (metal) 0.8*0.4*2 PWM – 10
Bench workbench with vice 2*0.5*0.75-1 VS - 3
Four-post lift 4*3 FOG - 4949201
Computer diagnostic station 1*0.5*1.7 Techno - 2000
Tabletop hydraulic press 1.5*0.52 ASG – 10t
Toolbox 0.8*0.5*0.8
Two post lift 1.5*2.5 PDG – 3500
Universal tool kit 0.5*0.3 JONNESWAY
Chest for metal waste 1.5*1*0.5 Homemade
Pneumatic impact wrench HANS ½ // SQ
Puller set
Torque wrench
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Calculation of the maintenance station staff.

At the production site of a service station there may be the following categories of workers:

Essential workers

Auxiliary workers

Engineering and technical workers

Junior service personnel

4.4.1 Calculation of the number of main workers:

We calculate the number of main workers in the mechanical section by profession with a preliminary determination of the annual time fund per worker:

We make the calculation using the formula:

R pcs. = , Where

F floor = (D r.g. - D otp. - N)*T cm.(hours), where

D r.g.– number of working days per year: D r.g. = D k -D c -D pr, where

D g– number of days in a year;

D in– number of days off;

D pr– number of holidays per year;

D otp. – vacation days (24 days);

N– absence from work for a valid reason (14 days);

T cm. – shift duration (8 hours);

D r.g. = 365-105-11=249 days;

F floor = (249-24-14)*8=1688 hours.

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We calculate the main workers by profession in the mechanical section:

R pcs. (welded) = 4350/1712 = 2.54

I assume the number of welders is 3 people.

R pcs. (milling) = 11020/1712 = 6.43;

I assume the number of milling operators is 6 people.

R pcs. (therm.) = 2900/1712 = 1.69;

I accept the number of thermal operators equal to 1 person.

R pcs. (drills) = 3480/1712 = 2.03;

I assume the number of drillers is 2 people.

R pcs. (current) = 4350/1712 = 2.54;

I accept the number of turners equal to 2 people.

R pcs. (sled.) = 2900/1712 = 1.69;

I assume the number of mechanics is 2 people.

The total number of workers in the mechanical section is 16

Number of main workers at the maintenance and repair site:

We hire a staff of auto mechanics in the maintenance and repair area in accordance with ONTP standards 01-91 (2 people per post) and the estimated number of posts. It is equal : R pcs. = 2*15 = 30*2=60 people.

Total the number of main production workers at the designed service station is 16+60=76 people

4.4.2 Calculation of the number of auxiliary workers:

The number of auxiliary workers can be determined by three methods:

a) on the labor intensity of auxiliary work.

b) according to workplace service standards.

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c) enlarged, as a percentage of the number of main workers.

When calculating, we use the third method (15 - 20% of the number of main workers): 76 * 0.18 = 13.68 we accept R aux. =14 people.

Breakdown by profession:

1. Repairman – 5 people;

2. Electrician – 5 people;

3. Storekeeper – 4 people.

4.4.3 Calculation of the number of engineers and specialists:

The number of engineers and junior service personnel is determined in accordance with the staffing table.

According to the staffing schedule we accept:

Engineers: master – 2 people;

mechanic – 2 people;

MOP: cleaning lady – 2 people.

Table 2. “Summary sheet of site workers”:

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4.5 Payroll calculation.

4.5.1 Payroll of main workers:

The main workers at the service station are paid according to the piece-rate form of remuneration. This form of remuneration offers a worker’s salary depending on the volume of work performed and an additional bonus for fulfilling the plan. It helps to increase labor productivity.

The planned basic wage fund for production workers is determined based on the planned labor intensity of the work, applied tariff rates and the level of bonus payments according to the following formula:

Basic = T year. × C hour.× To pr. [rub.], Where

Basic. – the main wage fund for service station production workers;

T year. – annual labor intensity of work at production sites (persons/hour);

K pr. – coefficient of additional payments for the bonus system (1.3);

C hour– hourly tariff rate RUB/hour;

4.5.2 Payroll fund of the mechanical section:

Basic =29,000*80*1.3=3,016,000 rub.

Additional wage fund (10% of the basic salary):

Z extra =3,016,000*0.1=301,600 rub.

Total payroll:

Z total. =3 main +3 extra

Z total. =3,016,000+301,600=3,317,600 rub.

Unified Social Tax = 3,317,600*0.342 = 1,134,619.2 rubles.

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Z avg. =3 total /N slave *12,

N work.– number of site workers;

12 – number of months.

Z avg. =3,317,600/16*12=17,279.16 rub.

4.5.3 Payroll fund of the maintenance and repair section:

Basic salary fund:

Basic =90,350*120*1.4=15,649,200 rub.

Additional salary (10% of basic salary):

Z extra =15,649,200*0.1=1,564,920 rub.

Total payroll:

Z total. =3 main +3 extra

Z total. =15,649,200+1,564,920 =17,214,120 rub.

Unified social tax (34.2% of the total):

Unified Social Tax = 17,214,120*0.342 = 5,887,229.04 rub.

Average monthly salary per worker:

Z avg. =3 total /N slave *12,

N work.– number of site workers;

12 – number of months.

Z avg. =17,214,120/60*12=23,908.5 rub.

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4.5.6 Wage fund for auxiliary workers:

To remunerate auxiliary workers, a time-based bonus form of remuneration is used

Table 3: “Calculation of the main wage fund for auxiliary workers”

Additional salary fund (10% of the basic salary):

Z extra =1,689,704*0.1=168,970.4 rub.

Total payroll:

Z total. =3 main +3 extra

Z total. =1,689,704+168,970.4=1,858,674.4 rub.

Unified social tax (34.2% of the total):

Unified Social Tax = 1,858,674.4*0342 = 63,566.64 rubles.

Average monthly salary per worker:

Z avg. =3 total /N slave *12,

Z avg. =1 858 674.4/14*12=11063.53 rub.

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4.5.7 Salary fund for engineers and specialists:

Table 4 “Calculation of the total wage fund for engineers and employees”

№ Name positions Quantity, pcs. units Resolution Monthly salary, rub. Monthly salary fund, rub Additional payments Annual salary fund, rub
% sum
engineers
1 Master 13-14 23 000 46 000 18 400 772 800
2 Mechanic 12-13 21 000 42 000 16 800 705 600
Total 1 478 400
MOP
1 Cleaning woman 1-3 8 000 16 000 3 200 230 400
Total 230 400

For engineering workers:

Unified Social Tax = 1,478,400*0.342=505,612.8 rubles.

The total salary for engineers is equal to the basic salary. The average monthly salary for engineers is determined by the formula:

3 average month 1 person = 3 total / (R itr. × 12)

3 average month 1 person = 1,478,400/4*12=30,800 rub.

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For MOP workers:

Contributions for social needs amount to 34.2% of the salary amount, and are calculated as follows:

Unified Social Tax =230,400*0.342=78,796.8rub

The total salary for MOS is equal to the basic salary. The average monthly salary for MOP is determined by the formula:

3 average month 1 person = 3 total / (P mop × 12)

3 average month 1 person = 230,400/2*12=9,600 rub.

All data on wages are taken from service stations in Kaluga:

1. C hour.– hourly tariff rate: for workers of the mechanical section – 80 rubles/hour; for workers in the maintenance and repair area – 100 rubles/hour.

2. The bonus amount for main workers is 30%;

3. The tariff rate for auxiliary workers is 60 rubles/hour.

4. Monthly salaries: 1) Foreman - 23,000 rubles.

2) Mechanic – 21,000 rubles.

3) Cleaning lady – 8,000 rubles

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4.6 Calculation of the cost of restoring the VAZ-2109 steering rack

1. Determine the cost of the worn part:

Part weight – 1.3kg.

The price of a new part is 7,000 rubles.

From =7,000/2=3,500 rub.

2. C m – raw materials and materials.

C m = K m * C zpo

K m – for welding work – 0.7…1.1:

C m =0.9*112.8=101.52 rub.

3. With zpo – the basic salary of personnel engaged in restoration

S zpo =T pcs *T st, where

T pcs – piece time per part;

T st – tariff rate for main workers (80 rubles/hour).

With salary =1.41*80=112.8 rub.

4. With salary - additional salary 10...18% of the basic salary.

With salary =0.1*112.8=11.28 rub.

5. Unified Social Tax – 34.2% of (With zpo + With zpd)

Unified Social Tax=(112.8+11.28)*0.342=42.43 rub.

6.TsNR - a comprehensive cost item for the workshop.

CNR = K c * S zpo, where K c = 0.85 – 1.05

TsNR=0.9*112.8=101.52 rub.

7.ZNR - factory overhead or general production expenses.

ZNR = K z * S zpo, where K z = 0.55 – 0.7

ZNR=0.7*112.8=78.96 rub.

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8.Costs for maintenance and operation of equipment:

C o = K o * C zpo, where K o = 0.65 – 0.85

C o =0.85*112.8=95.88 rub.

Let's find the production cost:

S/S pr = S from + S m + S zpo + S zpd + ESN+ TsNR+ ZNR+ S o

S/S pr =3,500+101.52+112.8+11.28+42.43+101.52+78.96+95.88=4,044.39 rub.

Steering Diagnostics

General information

Since steering problems affect multiple systems, all systems must be taken into account when diagnosing problems. To avoid being misled by false symptoms, you should always road test the vehicle first.

General diagnostics

Check the power steering for leaks. Also check the power steering fluid level and the tension of the pump drive belt.

The operation of a vehicle with faulty steering is not without reason prohibited by the current legislation of the Russian Federation. It's no secret that on our roads the chance of getting into a traffic accident is relatively high, even with ideal driving. When the number of registered cars crosses the fifty million mark, the busyness of the traffic itself becomes a serious risk factor. Failure of any important component of the car in such conditions can end extremely badly. To ensure proper and safe driving, it is important to carry out diagnostic measures in a timely manner. A procedure such as steering diagnostics deserves special attention. Therefore, today we will try to consider it in a little more detail.

One of the most common in this case will be the occurrence of gaps between steering parts. In a professional environment, such gaps are most often called backlash.

They appear as a result of various unfavorable external influences, the occurrence of which is simply inevitable in traffic conditions. In addition, active use of a vehicle is associated with deterioration of the condition of parts even without external influences, since no one has canceled the friction between various components. The more play, the more intensively the steering column wears out. As a result, the chance of getting into a traffic accident gradually increases.

Since the occurrence of play is one of the most common problems with the steering mechanism, steering diagnostics are largely aimed at identifying this particular defect. To conduct a competent inspection of the mechanism elements, a specialist may need an overpass or an equipped pit. In some cases, it is possible to use suitable equipment, but often the attentive eye of a specialist is quite sufficient.

Steering diagnostics is a relatively simple procedure, which, however, has several important nuances. This operation will not require the involvement of a large number of specialists or serious resources, however, the quality of its implementation is directly related to the qualifications and experience of the performer. Therefore, steering diagnostics should be carried out only in trusted auto repair shops and only by competent specialists. Otherwise, the reliability of the results obtained may be extremely doubtful.

If you need steering diagnostics, contact our expert organization. We will carry out all necessary activities quickly, efficiently and inexpensively

In what cases is steering diagnostics necessary?

It is advisable that steering diagnostics be carried out regularly. Moreover, not separately, but as part of the general diagnostics of the main vehicle systems. This approach will ensure proper controllability and safety of the car over a long period of time. It is no secret, however, that most car owners prefer to ignore the benefits of regular diagnostics, carrying out the latter only when problems arise. Therefore, let's look at this issue in a little more detail.

Steering diagnostics will be necessary in the following situations:

  • the occurrence of unfamiliar noises during the rotation of the steering wheel;
  • the occurrence of strong knocking in the steering wheel when the car moves on a bad road;
  • tight, difficult rotation of the steering wheel.

All the circumstances mentioned are a serious reason to seek help from specialists. If the driver is not concerned about the safety (of his own and those of others), then he should also remember that over time, minor defects can become much more significant. In other words, fixing a problem after a few months can cost much more than if the problem were solved immediately after the fact. occurrence. Therefore, prompt diagnostics of the steering and its subsequent repair is also an excellent way to protect yourself from potential costs.

Steering diagnostics is also a preliminary step for all procedures involving the replacement of steering gear components.

Any questions? Contact us by phone, email, or through comments on this post. Our specialist will clarify in detail all the ambiguities that have arisen and advise on the cost of the service in your specific case.

Steering diagnostics. Main malfunctions of the mechanism

Difficult rotation of the steering wheel, mentioned just above, is usually the result of insufficient oil in the crankcase of the mechanism. Common causes of malfunction include:

  • insufficient tire pressure;
  • wheel imbalance;
  • damage to suspension components;
  • deformation of steering drive elements.

If we are talking about a worm-type system, then most often the main cause of problems is a violation of the gap in the engagement of the elements.

What is the procedure for diagnosing steering?

Like many other diagnostic measures, steering diagnostics begin with a visual inspection. All the main components of the mechanism, as well as the elements associated with it, are studied. In particular, the specialist evaluates the geometry of all those parts of the suspension that are connected to the steering.

Checking backlashes is the main stage of diagnosis, which is a complex of visual and instrumental examinations. As noted earlier, in some cases the experienced eye of a specialist may be quite sufficient. However, to increase the accuracy and reliability of the results, professionals usually use special equipment. In particular, a dynamometer-play meter is a precise device that allows you to determine the angular movement (play) of the steering wheel of a vehicle.

If we are talking about power steering, then the hydraulic system can be checked separately.

In some cases, initial steering diagnostics do not lead to the results that experts initially expected. If a malfunction is present, but its main cause cannot be determined, the wheel angles can be checked. The wheel alignment procedure can help with this.

Repair

As a rule, steering diagnostics reveals the need for urgent repairs to system faults. The nature of the measures taken directly depends on the specifics of the detected problems.

Often, a specialist discovers parts that are so worn out that the question of how they continued to function properly for so long becomes very interesting. In this case, the only possible way to return the mechanism to its previous condition is to replace those elements whose wear is too high with suitable spare parts.

If the steering diagnostics revealed only minor defects, be it cracks or minor deformations, it will be quite possible to get by with cosmetic repairs: fix something, fix something. In this case, the cost of the work will be quite low. However, those car owners who turn to us for help immediately after a problem arises most often have a chance to get by with such low costs. Otherwise, cosmetic repairs will hardly be possible.

It is noteworthy that repair work in this case almost always requires preliminary dismantling of the steering wheel. Unlike diagnosing the steering, which compared to many other procedures can be considered a relatively simple procedure, repairing the same mechanism is a rather delicate process, very sensitive to the experience and qualifications of the specialist. The list of necessary equipment to fix the problem will also be somewhat wider than the list of equipment for diagnosing it.


Steering Diagnostics

^ Steering (RU) is one of the most critical vehicle systems. Through the control unit, the driver carries out the main control actions on the car, so even minor malfunctions in the operation of the control device have a noticeable effect on the controllability and trajectory of the vehicle. Switchgear malfunctions cause 15% of all road accidents that occur for technical reasons. Modern reactor plants are quite reliable, but if they fail, the consequences are often catastrophic.

^ Health Options steering controls are installed according to DSTU 3649-97 standard. This is the total angular clearance and the maximum force on the steering wheel (RW) (see table). In addition, there are a number of qualitative

new requirements. The following are not allowed:  movements of switchgear parts and assemblies not provided for by the design relative to each other or the supporting surface;  damage and deformation of the reactor plant, determined visually;  spontaneous rotation of the control valve from the neutral position on the vehicle with a control valve amplifier during its stationary state and with the engine running;  leakage of working fluid in the booster hydraulic system. The belt tension of the power steering amplifier pump and the level of working fluid in the reservoir must meet the requirements of the IE. The maximum rotation of the steering wheel should be limited only by the devices provided for by the design of the vehicle. The steering wheel should rotate without jerking or jamming throughout the entire range of its rotation angle.

^ Control methods according to DSTU . The vehicle is checked in running order. The wheels must be installed on rotating devices with bearing supports that can move in the longitudinal and transverse directions when turning (“floating supports”). Before checking, the steered wheels must be in a position corresponding to straight-line movement. The DTS engine equipped with a control amplifier must operate at minimum idle speed.

The steering wheel must be turned smoothly, without jerking, in two opposite directions. At the moment the force on the steering wheel reaches 10 N or the rotation of any of the steered wheels begins, the angles of rotation of the steering wheel must be recorded. The maximum force on the steering wheel is also recorded throughout the entire range of steering angles. It is allowed to determine maximum effort on a vehicle moving at a speed of no more than 10 km/h.

The value of the total angular clearance in the switchgear is determined as the sum of the rotation angles in opposite directions. The difference between these angles should not exceed 20% of the larger one. (Note that this requirement can be met if the controller knows exactly the average position of the control gear - and this is not so simple. At the diagnostic station, it is convenient to place a control station check post after the roller stand with its own drive. When the rollers rotate, the steered wheels will definitely be set to the middle position - in any other case, the car “drags" to the side. But even here, a large difference in camber on the right and left wheels can interfere).

Impact of RU on the database. Why are these two indicators highlighted? An increased angular clearance means a large free play (play) of the steering wheel, which means a delay in the vehicle’s response to the driver’s control inputs. High resistance to turning the steering wheel means increased driver fatigue and control lag. But this is not the worst thing: these changes accumulate gradually, the driver feels them and, as best he can, adjusts his manner of manipulating the steering wheel.

Much more dangerous sudden failures. The reactor plant experiences significant alternating loads under constant exposure to dust and moisture. This causes rapid wear, which can lead to parts failure and, as a consequence, serious accidents. The most dangerous in this sense are cutting off the ball pins of the rods and breaking the transverse rod. These breakdowns lead to an instant loss of control, and since they occur while the car is moving and the driver, as a rule, does not have time to brake, the car abruptly changes direction and slides into the oncoming lane or off the road altogether. Both threaten the destruction of the machine and the death of people. These breakdowns occur under increased loads: when driving through thick mud, leaving a rut, moving over an obstacle and sharp maneuvering at high speed. The first three cases rarely cause a disaster, because... the speed is low. The last case is the most dangerous. Less dangerous, but also very unpleasant, is the sudden displacement of the steering mechanism if its fastenings are loose. In this case, controllability is not completely lost, but the position of the wheels changes abruptly, which can cause the car to throw. DSTU does not provide recommendations for testing and identifying pre-failure conditions; the methods specified by the standard do not allow this to be done. Therefore, DM methods and tools must ensure early identification of the described hazards.

In addition, modern switchgear, especially with amplifiers, suffer from other defects, albeit less dangerous, but also interfering with control. They have been studied better, they can be diagnosed and predicted to some extent.

Basic reasons for the deterioration of the technical condition of the reactor plant– wear; The most dangerous period is the period of progressive wear (135...155 thousand km). In ball joints, adhesive and abrasive wear is observed due to large contact loads (lubricant is squeezed out, the oil film is torn, and friction causes heating and welding of individual microroughnesses with subsequent rupture). Fatigue is caused by alternating loads in the rods and accelerates with increasing gaps when impacts begin. Microcracks appear, create stress concentrations, cracks develop quickly, which leads to parts breaking: either the fingers are cut off, or the socket is broken and the finger pops out. On some DTS this can be prevented by adjustment, on others no adjustment is provided. (The general rule: designers strive to reduce the number of adjustment points, introduce automatic adjustment - and this often worsens the technical condition of the car, since it deprives the driver and mechanic of the opportunity to intervene, and “automatic adjustment” has its own limitations and disadvantages). In a hydraulic booster, the interfaces of which are well sealed, abrasive wear is low, and cases of fatigue failure are more common.

Common malfunctions and methods for diagnosing them are described in detail, for example, in the textbook by A.N. Yurchenko. and others. “The practice of diagnosing cars.”

Most common RU diagnostic tool– backlash dynamometer. The device itself is secured with screw clamps on the rim of the steering wheel, and the pointer arrow is mounted on the steering column. The RK is turned in one direction and then in the other direction through a dynamometer. The play meter scale rotates along with the wheel; a fixed arrow indicates the angle of rotation. In this case, the steered wheels either rest on floating platforms, as prescribed by DSTU, or are suspended (then the right wheel is clamped with a lock). Floating supports may have a system for measuring the steering angles of the steered wheels. It provides additional information that characterizes the correctness of the ratio of turning angles (for stable movement without increased tire wear, it is necessary that when turning, the outer and inner wheels roll along arcs of circles, the centers of which coincide with the center of rotation of the car; for example, reducing the turning angle of the outer wheel by 1  causes an increase in tire wear by 54%, an increase by 1 - by 28%; wear is observed in the shoulder areas of the tread). This ratio may be violated either due to an excessive change in the length of the transverse rod when adjusting the toe, or due to a violation of the dimensions of the trapezoid caused by deformation or unsuccessful repair of its elements.

More perfect stands for diagnosing RU. All of them are known in single copies and were not mass-produced. Stand KRU-210 was created at the Lugansk Mechanical Engineering Institute under the leadership of A.V. Gogaizel. The stand has a support platform with wheel fixing elements, a rotation drive and a rotation angle meter. The second wheel rests on a floating faceplate, which is connected through a pantograph to the same meter as on the supporting platform. The third block of the stand is the so-called. “robot” is a reversible device for rotating the rotor. The robot is mounted on the steering column. The drive electric motor rotates the CV with a rubber-coated roller through a gearbox and a torque sensor. There is also a rotation angle sensor. Over the course of several double strokes of the robot, an X-ray recorder records signals from two sensors in the form of a diagram of the dependence of torque on the angle of rotation (“diagnostic portrait”). Fundamentally, the diagram reflects the values ​​of each gap in the kinematic chain of the steering drive and the resistance forces at each interface. In fact, it is not possible to separate them, and the diagnosis is made based on the enlarged characteristics of the portrait, identifying the main violations of the technical condition of the steering drive itself and the power steering. Such a stand can be seen in Kharkov at the KamAZ vehicle diagnostic station in motor depot No. 5. The presence of a support platform and a faceplate with meters allows you to evaluate the play in the steering linkage, between the two steered wheels, which is inaccessible to a conventional play dynamometer. This solution was first proposed at the stand of SKRU-71 HADI.

SibADI scientists developed such stands in an interesting way. The main feature: the possibility of simultaneous loading of the switchgear from the side of the steering wheel and from the side of the steered wheels. This stand simulates maximum workloads. Under their influence, the above-mentioned displacements of the switchgear units can occur, cases of unreliable fastening of the wheel disks are revealed (if there is a nick on the stud, the torque wrench shows normal tightening, but in fact there is play), and sometimes breakdowns of unreliable parts occur. The already discussed thesis works again: if it is impossible to detect a pre-failure state, then It’s better to break an unreliable part when diagnosing on a bench than in an emergency on the road.

Brake system as an object of control and diagnostics

^ Performance indicators of the braking system. According to long-term statistics, 58% of all road accidents caused by technical faults are associated with braking systems (TS). Therefore, vehicle inspection is the most important of the vehicle OBD system inspections performed in operation, and therefore vehicle performance indicators, their permissible values ​​and inspection modes are determined by standards. The standards of one group regulate the requirements for products of the automotive industry, i.e. to road vehicles (RVs) produced by factories, the second - to RVs in operation. Developers include in the design of the vehicle such capabilities that must meet the requirements of industrial standards. The latter are high enough to create a reserve for deterioration of the technical condition of the vehicle in operation. The limit of this deterioration is prescribed by the operating standards on which the requirements of the Road Traffic Regulations are based. Thus, the upper limit of steady-state deceleration set by the designers may be 9-10 m/s 2 for passenger cars; the industrial standard will prescribe values ​​of 7-8 m/s 2 , and the operational standard – 5.5-6 m/s 2 . The latest requirements are the norm for traffic police and enterprises performing vehicle maintenance.

In Ukraine, the standard DSTU 3649-97 “Road vehicles. Operational safety requirements for technical condition and control methods” instead of the canceled GOST 25478-91. There are two types of testing of the service brake system (RSS): road and bench. Road tests RTS are performed on horizontal area dry and clean roads with hard surface equipped condition of a road vehicle (VV) with a driver and measuring instruments (if necessary, also with a test operator) with cold brakes (RTV has not been used for 30-40 minutes; for comparison: according to UNECE Rule 13 for new vehicles , the brake is considered cold if the outer surface of the brake drum has a temperature of no more than 100). The initial braking speed should be between 35 and 45 km/h. The force on the brake pedal is 490 N for DTS categories M 1 and N 1 and 686 N for other categories. During the braking process, the driver is not allowed to adjust the trajectory of movement if this is not required to ensure DB, otherwise the test result will not be counted. The condition of the RTS is assessed by the actual value of the braking distance, which should not exceed the standard specified in Table 7.1.

Table 7.1 Standard braking distance values ​​for road vehicles in operation (according to DSTU 3649-97)


DTS type

DTS (tractor) category

Braking distance, m, no more than values,

Calculated by formulas


Singles

M 1

V o  (0.10 + V o / 150)

DTS

M 2, M 3, N 1, N 2, N 3

V o  (0.15 + V o / 130)

Road trains

M 1

V o  (0.15 + V o / 150)

M 2, M 3, N 1, N 2, N 3

V o  (0.18 + V o / 130)

Here V o is the initial braking speed in km/h.

According to DSTU, it is allowed to evaluate the performance of the RTS by the steady deceleration of the RTS (j set), which must be at least 5.8 m/s 2 for RTS category M 1 and 5.0 m/s 2 for all others (taking into account road trains based on the RTS category M 1). In this case, it is necessary to control the response time of the brake system, which for a vehicle with a hydraulic drive should be no more than 0.5 s and for a vehicle with another drive - no more than 0.8 s. According to DSTU 2886-94, the braking system response time ( s) is the time interval from the start of braking to the point in time at which the deceleration (braking force) of the brake system takes on a steady-state value.

At bench tests The criteria for the technical condition of the vehicle are the total specific braking force and the response time of the vehicle on the stand, as well as the axial coefficient of unevenness of the braking forces for each axis. The total specific braking force ( t) must be at least 0.59 for single DTS of category M1 and 0.51 for all others. In this case, the maximum value of the unevenness coefficient of any axis (Kn) should not exceed 20% in the range of braking forces from 30% to 100% of the maximum values. These criteria are calculated using the following formulas:


 t =  Р t maxi / (M a p  g),

(7.1)

Where

R t maxi

– maximum value of braking force on the i-th wheel, N; summation is made from i = 1 before n, where n is the total number of wheels equipped with brake mechanisms;

M ap

– total vehicle weight, kg;

g

– free fall acceleration, 9.80665 m/s 2 ;

Kn = R tl - R tp /R t max  100%,

(7.2)

Where

R tl, R tp

– values ​​of braking force on the left and right wheels of one axle, respectively, N;

R t max

– the greater of the two indicated braking force values.

It is worth noting that according to GOST 25478 Kn it is calculated slightly differently:

The response time of the braking system on the stand ( sp) is the time interval from the start of braking to the moment at which the braking force of the wheel of the vehicle, located in the worst conditions, reaches a steady value (defined according to DSTU 2886-94).

At the stand, the DTS must be tested in a state full masses. It is allowed to test DTS with a pneumatic drive in running order. In this case, the maximum wheel braking forces and response times must be recalculated. The total specific braking force and response time on the stand should be determined as the arithmetic average of the results three tests. As on the road, tests should be carried out with “cold” brakes.

Note that the requirement to perform a bench test is in the state full mass comes from the limited capabilities of most power stands to implement braking forces (0.7...0.9 of the effective load on the wheel; for inertial stands it is higher - 1.0...1.2). This requirement is unrealistic; It is no coincidence that the standard allows for vehicles with pneumatic drive (i.e., most trucks and buses) to be tested in running order. Let’s say that when inspecting cars at the State Traffic Inspectorate, you can seat the driver, the inspector and two or three people from the queue. But for minibuses, not to mention trucks and buses with hydraulic brakes, this is not feasible. With regular checks at ATPs and service stations, this requirement will never be met. The solution may be to artificially additionally load the wheels being tested, but stands with additional loaders have not become widespread.

All current standards use a simplified representation of the braking process to calculate standards. The real braking diagram of a car has a rather complex configuration - see, for example, Figure 7.1. The real diagram is replaced by an idealized one, this is how a normal braking diagram is usually presented, highlighting on it the delay section t W, the rise section t H (the sum of these two durations is called the response time t C) and the steady-state braking section t SET. In the delay section, the forces of rolling resistance, air resistance and friction in the bearings (as well as the friction force of the linings on the brake drum or disk, if there are no gaps due to improper adjustment) create a coast-down deceleration j B In the section of steady braking, the deceleration is considered constant - steady (j UST). It is believed that in the growth section the deceleration increases linearly.

Figure 7.1 - Braking diagram:

A – real, b – idealized,

B – simplified

It is enough to simply integrate the idealized dependence of deceleration on time and obtain the curves of speed and braking distance. However, they usually go to further simplification: they consider the run-out deceleration to be equal to zero, and the section of steady-state braking begins from the moment of time t SU = t W + t N /2 (we will call this moment the conditional response time). It is with this representation that the braking distance is calculated:

It is easy to see that such a simplification reduces the accuracy of calculating the braking distance by only 1.2...1.5%.

So, to check the RTS on the road It is enough to measure the braking distance or two parameters that determine it: steady-state deceleration and conditional response time - and the latter is practically impossible, we must measure the delay time and rise time to find t SB. To check RTS at the stand in formal accordance with the standard, you need for each wheel measure braking force and response time.

However, in addition to the RTS, the car also has a parking brake system (SBS), an auxiliary brake system (ABS) and an emergency vehicle. The latter is usually one of the circuits of a multi-circuit RTS, which remains operational if the other circuit malfunctions. VTS is either the same STS, or an engine brake (on diesel trucks and buses, and recently on passenger cars, for example, on some modifications of the VAZ-2109). Abroad, on heavy vehicles, for example, on heavy-duty dump trucks, transmission or wheel retarder brakes are used, most often electric induction brakes operating on Foucault currents. These retarders effectively reduce the speed to values ​​of about 15 km/h, after which the car is slowed down by a conventional RTS until it comes to a complete stop.

According to DSTU 3649 monitoring the effectiveness of STS performed by road or bench testing. The STS must hold the full weight vehicle of categories M and N in a stationary state for at least 5 minutes on a road section with a slope of 16%, the vehicle of the curb weight of category M on a slope of 23%, category N on a slope of 31%, and tests should be carried out for two positions of the vehicle. on a slope: front wheels up and down. The force on the control should not exceed 392 N for category M1 and 588 N for other categories. During testing at the stand the value of the total specific braking force must be at least 0.16 of the total weight.

^ MTC check the standard provides road test only. In the range from 35 to 25 km/h according to the speedometer, the steady-state deceleration must be at least 0.5 m/s 2 for a vehicle with full weight, and at least 0.8 m/s 2 for a vehicle in running order.

^ Selecting a test type . The main type of tests according to the road standard. Can they be performed under operating conditions? Tests must be carried out on horizontal flat section of road with hard surface dry and clean condition. This is not possible during and after rain, snowfall and winter, when there may be snow or ice on the surface. In our climate zone, these conditions exclude half of the year, or even more. Further, the tests involve the risk of skidding during emergency braking. This means that the road section must be free from traffic and not have dangerous ditches, fences or slopes. In practice, this means that for road tests you need to build a special track. This was done once in Zaporozhye. The path was 12 m wide and long enough for acceleration and braking, including with bad brakes. A regular ATP cannot afford this. Therefore, only bench tests are realistic. Our stand is always placed in a closed heated room; it ensures the accuracy and safety of measurements at any time of the year and day, in any weather. But this imposes additional requirements on the stand: it needs to check not only RTS, but also STS and MTC. There are no difficulties with the latter, but to check the STS it is necessary to implement a completely static mode. Whether this is possible, we will figure it out later.

UD requirements. If the OD has identified an inoperable state of the vehicle based on some parameter, it is necessary to localize the defect causing this state. Obviously, malfunctions must somehow affect the operation of the braking system as a whole or a specific braking mechanism, changing the output parameters and the appearance of the braking diagram (Figure 7.2).

Figure 7.2 – Manifestation of vehicle malfunctions on the brake diagram: a – normal diagram; b – the delay time is increased (the gaps are large); c – there is no delay section (no gaps); d – the deceleration of the free run-out of the wheel is increased (the bearings are overtightened); d – rise time increased (air in the system); e – increased steady-state deceleration (block jams); g – reduced deceleration (oiling); and – there is no braking (the brake does not work); j, l – falling diagram in the section of steady braking (leakage); m – wavy diagram (ellipse); n, p, p – convex diagram; c – saddle diagram (reduced contact area)

The delay time is large (b) if the free play of the brake pedal and (or) the clearances in the brake mechanisms are increased. In addition, some brake boosters, for example, GVU, act as a gas cushion in the drive, increasing both the lag time and the rise time. The delay time on one of the wheels can increase sharply if the flow area of ​​the leads to the corresponding wheel brake cylinder is reduced: the copper tube is jammed, the inlet is clogged. While the pedal is moving and there is a noticeable flow rate, dynamic hydraulic resistance creates a backstop, the liquid flows to where the resistance is less, and only when the pedal stops and the flow speed has dropped to almost zero, the backpress disappears and the liquid can flow into this cylinder. The wheel mechanism will then work normally, only with a great delay.

The rise time is increased (e) as the system stiffness decreases: the pedal moves and the pressure builds up slowly. Most often this happens if air has entered the hydraulic system. Other reasons: loss of hose rigidity (swelling) with cord rupture, increased elasticity of the brake drum after numerous resharpenings during repairs. If the rise time is increased on all wheels, most likely air is entering the system near the master cylinder (little fluid in the reservoir or worn cuff); If the rise time is increased only on one wheel, then there is air in the wheel cylinder - possibly due to a poor condition of the cuff. In this case, one can expect reduced braking force: if air is sucked in through the cuff, then when you press the pedal, brake fluid will flow out through it and the oil contained in it will fall on the brake drum, which will reduce the coefficient of friction (CTf) - brake fluids consist of a mixture of alcohol and castor oil.

The value of the steady-state braking force (deceleration) can be reduced (g) in the brake mechanism due to incorrect adjustment - the lining is taken by the heel - or due to a drop in the CTR between the lining and the drum (disc), for example, due to oiling. If the braking force is reduced on all wheels, then you should look for a malfunction in the drive (there is not enough fluid in the master cylinder reservoir, the amplifier does not work).

Finally, there is a group of malfunctions associated with deteriorated contact in the rubbing pair of the brake mechanism (n - c). To understand their essence, it is necessary to understand the nature of friction. A brake is a device that converts the kinetic energy of a car into heat due to the work of friction forces. The heat released during braking heats the friction zone, and then is gradually released into the atmosphere, mainly through the brake drum (disc), since the non-metallic lining has much worse thermal conductivity. Emergency braking, as in an emergency or when testing the brake system, lasts a few seconds, so the heat almost does not have time to spread beyond the friction zone and the layers of the drum close to it. During the braking process, the temperature first rises rapidly, reaches a maximum, and then decreases, but not to zero (Figure 7.3). This is explained by the fact that as braking progresses, the speed drops, and with it the kinetic energy supplied per unit time, absorbed by the brake and converted into heat. The maximum is reached when the heat supply and removal are equalized, and then heat removal dominates and the temperature drops. Under normal technical condition of the rubbing pair, the average temperature of the friction surface can increase by approximately 100°C from the initial one. If the pauses between braking are long, the brake will have time to cool down. If you brake frequently, for example, in a big city with many traffic lights or in the mountains, the brake does not have time to cool down and its temperature can rise much more.


Figure 7.3 – Change in brake temperature during single braking

If the brake is poorly adjusted or the lining is worn unevenly, the actual contact area in the friction pair will be less than the nominal area of ​​the lining, but the amount of heat input will remain the same, and each square centimeter of the actual contact area will heat up more, for example, up to 300 or 400°. Such high values ​​are not surprising: the contact of solids is actually a collection of many microcontacts, and in each microcontact the temperature can reach, for example, 1600°C. And the numbers mentioned above are the temperature averaged over the total contact area. So, the temperature of the friction surfaces in the brake mechanism can increase sharply when working in difficult conditions and when the technical condition of the friction pair is deteriorated, leading to a decrease in the actual contact area. What does this lead to?


In school physics, it is customary to consider the KTP for a given pair of materials to be a constant value. There is only a distinction between resting Ktr and sliding Ktr, which differ by about a factor of two. This is a very simplified view. In fact, KTr is not a constant value; it depends significantly and similarly on contact pressure, sliding speed and temperature (Figure 7.4).

Figure 7.4 – General nature of the dependence of the friction coefficient on contact pressure, sliding speed and temperature


The more perfect the crystal lattice of the rubbing materials, the less the Ctr changes. For non-metallic and generally non-crystalline materials, for example, rubber tires or brake lining material (usually asbestos fibers and crumbs bound with rubber or synthetic resin), the dependence is quite noticeable. For friction materials, according to experts, the main factor is temperature, and speed and pressure affect KTP only insofar as they change the temperature, and therefore, when studying the frictional heat resistance of such materials, only the influence of temperature can be taken into account. And it is very large (Figure 7.5).

Figure 7.5 – Typical dependence of the coefficient of friction in the rubbing pair of a car brake on temperature

If we now consider together the graph of the temperature change during the braking process and this dependence, we can obtain a diagram of the change in braking force in the so-called section. steady braking. With full contact area and normal initial temperature, the maximum temperature is relatively low, the diagram is close to horizontal or slightly convex. As the actual contact area decreases, the maximum temperature increases, the diagram becomes more and more convex, and when the temperature goes beyond the first extremum, a saddle-shaped dip appears on the diagram. Analysis shows that this saddle may be a symptom of a dangerous reduction in actual contact area, which will cause the average steady-state braking force to become less than normal.

In some cases, the maximum on the braking diagram shifts to the beginning or end of the section of steady-state braking. All these are symptoms of a poor fit of the lining to the drum, signals that the brake needs to be adjusted or repaired (grind the drum, grind the linings). Sometimes you can see a maximum at the beginning of a section of steady-state braking, after which there is a uniform linear drop in braking force (Fig. 7.2, l). This is how a leak in the wheel brake cylinder manifests itself.

Calculations have shown that it is dangerous to reduce the contact area of ​​the lining with the drum to 50% of the nominal value. Does this happen in practice? We conducted a survey of the technical condition of linings in automobile enterprises and found that a contact area of ​​less than 50% occurs on 17% of passenger car linings and on 45-55% of truck linings (depending on the family). On heavy-duty dump trucks, a contact area of ​​50% is generally considered the norm. What are the reasons for these phenomena? Incorrect adjustment leads to the fact that the pad does not take the entire length, but only the toe or heel. When trucks have had the linings changed and not sanded down, they will only take the middle. Further, the pad may have a reduced contact width for various reasons. If the edge of the pad is deformed, the lining will only be taken with the left or right side. When, after a series of regrinding, the brake drum has become too thin, during braking it will expand into a cone as a result of heating, and the pressure on the outer edge of the lining will decrease. If the lining is not glued, but riveted, then dust and sand accumulate in the recesses under the heads of the rivets, wears out the mating parts of the drum, and the two strips of the lining are disabled. Finally, grains of sand cause line wear on the linings and drums.

Hence, reduced contact area drum pads – common fault. Under emergency braking conditions, especially with previously heated brakes, it can lead to a sharp drop in braking force. This means that this malfunction is not only common, but also dangerous. The worst thing is that it is extremely difficult to notice it in action: while the driver performs only service braking with slight decelerations, the brake does not heat up, its efficiency is high. And failure will occur only in an emergency situation, that is, precisely when the greatest braking efficiency is required. This means that this malfunction is also very insidious. It is difficult to detect even when opening the brake mechanism. Usually a mechanic opens the brake, wipes the linings with a rag and inspects it. Can't be wiped! Often, non-working areas of the lining are powdered with dusty wear products; If you carefully inspect the pad without wiping off the dust, you can see the difference between the working and non-working areas. But with line wear, special methods are required to estimate the actual contact area. Conclusion: the UD method and means must detect all characteristic vehicle malfunctions, including those associated with a decrease in the contact area of ​​the lining with the drum (disc).

Sometimes the braking force in the steady braking section fluctuates (m). The reasons for this are the following: non-concentricity or ellipticity of the brake drum; warping of the brake disc; increased elasticity (compliance) of the brake drum after several resharpenings during repair - because of this, the pads stretch the drum, turning it into an ellipse.

So, for operational monitoring and testing of brake systems, a stand is needed that provides vehicle testing in accordance with the requirements of DSTU and simulates road testing of STS and VTS prescribed by DSTU; the stand and the UD method must be sensitive to all the main malfunctions of the vehicle, including a reduced contact area in the rubbing pair.

Control

Manufacturing and industrial technology

When diagnosing the steering wheel, the play of the steering wheel and the force required to turn it when the wheels are hanging are determined; friction losses are also checked; the fastenings and condition of the steering linkage joints are also checked. On vehicles with hydraulic power steering, play is measured with the engine running. In addition to the steering wheel play, it is necessary to check the clearances in the steering linkage joints by the relative movement of the ball pins and rod ends or heads when the steering wheel is sharply turned in both directions, the clearance in...

1 Steering diagnostics. Options. Equipment.

When diagnosing the steering wheel, the play of the steering wheel and the force required to turn it with the wheels hanging up (friction losses) are determined; the fastenings and condition of the steering linkage joints are also checked. The play is determined using a dynamometer-play meter mounted on the rim of the steering wheels. The angular displacement of the wheel is determined under the influence of a force of 10 N applied to the rim. This is necessary so that when measuring

eliminate inaccuracy due to elastic deformations of parts. On vehicles with hydraulic power steering, the play is measured with the engine running. In addition to the steering wheel play, it is necessary to check the clearances in the steering linkage joints (by the relative movement of the ball pins and rod ends or heads, when the steering wheel is sharply turned in both directions), the clearance in the steering wheel worm bearings relative to the column. The clearances in the engagement of the roller and the worm of the steering mechanism are checked by the longitudinal movement of the steering bipod shaft with the steering rod disconnected. Friction forces in mechanisms are controlled by the force applied to a dynamometer-backlash meter. The proper operation of the hydraulic booster depends on the oil level in the tank and the pressure developed by the pump during engine operation. These indicators are also checked. In a pneumatic hydraulic booster, the control unit controls the tightness of the air ducts and the operation of the tracking mechanism. The steering column mounts are checked by the relative movement of the mating parts and by direct testing of the tightening of the nuts.

2 BZD when performing repair work (washing/cleaning, assembly/disassembly, running-in of units)

1) All premises must have adequate lighting, ventilation, and exhaust gas exhaust.

2) When washing vehicles, cleaning and washing devices, vacuum cleaners, and mechanical washes are used; When chemically cleaning units, the installations are placed in isolated rooms.

3) Washing machines and various installations for washing and cleaning work must be equipped with local ventilation.

4) Steam-conducting pipes and installations with temperatures above 75 0 C, must have thermal insulation to prevent burns.

5) In addition to local ventilation suction, there must be general supply and exhaust ventilation.

6) When working with aggressive chemicals, it is necessary to use personal protective equipment: goggles, respirator, gloves, mask.

7) when working with electrical installations - grounding, rubber gloves, boots, mats.

8) Workbenches are separated with metal mesh.

9) when working on machines, use protective screens where shrapnel wounds are possible.

10) Use proper tools.

11) Equipment must be arranged with necessary gaps.

12) Units and parts that came into contact with leaded gasoline during work should be pre-washed with kerosene in special baths with local suction.

13) Units and parts weighing more than 20 kg must be removed, transported and installed using lifting vehicles. The force when lifting a load with a mechanism must be directed vertically; pulling loads with cranes is prohibited.

14) All fixed fixtures should be firmly anchored to prevent them from casting shadows.

15) Used cleaning material is placed in metal boxes with a lid. Drawers should be cleaned at the end of the shift to prevent spontaneous combustion.

16) When welding - protection of all parts of the body, masks with dark glasses, storage of gas cylinders in separate rooms.

17) It is prohibited to use open fire where there is a risk of explosion or ignition (battery, galvanic, woodworking shops).

18) All workshops must be equipped with first aid kits.

19) The width of passages and passages must comply with safe standards. It is prohibited to block passages, driveways and approaches to boards with fire tools and fire extinguishers.

4 Sources of financing for ATP, use of credit systems

Sources of financing:

federal budget;

budgets of the constituent entities of the Russian Federation;

centralized off-budget investment funds, etc.;

commercial bank loans;

funds from private investors, etc.

Credit systemusually considered as a set of credit and settlement relations, forms and methods of lending, and as a set of credit organizations (financial credit institutions).

Credit relations are associated with the movement of loan capital and include various forms of credit. The credit system as a set of financial and credit institutions accumulates free cash capital, income and savings of various segments of the population and lends them to firms, the government and individuals. Let us note that the credit system is closely related to the monetary system, so we speak purely about their totality - the monetary system.

The basis of the credit system has historically been credit organizations (financial credit institutions), primarily banks.

In market-type systems, there are traditionally a number of ways to attract financial resources to small businesses. This includes obtaining loans from government funds to support entrepreneurship, bank lending, attracting investments from international development institutions within the framework of small business support programs, and mutual lending. The priority of one or another method of financing small businesses or their combination is determined by the country’s established tradition of state and commercial financial and credit institutions.

The provision of credit resources is carried out on the basis and as applications are received from small businesses after preliminary agreement with the counterparty bank on the parameters and conditions for each loan.

Preference is given to lending to enterprises to modernize and expand production through the purchase of equipment and replenishment of working capital.


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Description of the presentation by individual slides:

1 slide

Slide description:

Topic: Steering diagnostic tools Steering device The steering of a car consists of a steering mechanism having a working pair (globoidal worm - double roller) with a gear ratio of 17: 1 in the middle position, and a steering gear, which includes steering linkage levers, a pendulum lever , bipod, middle rod and two side rods of the steering linkage

2 slide

Slide description:

3 slide

Slide description:

In a rack-and-pinion steering mechanism, force is transmitted to the wheels using a spur or helical gear mounted in bearings and a rack moving in guide bushings. To ensure backlash-free engagement, the rack is pressed against the gear by springs. The steering gear is connected by a shaft to the steering wheel, and the rack is connected to two transverse rods, which can be attached in the middle or at the ends of the rack.

4 slide

Slide description:

5 slide

Slide description:

General information about the technical condition of the steering During the operation of the car, depending on the conditions, the steering parts wear out, the attachment of some of them to the frame is broken, and deformation occurs - distortion of the geometric shape. Checking the condition of the steering drive elements and adjusting the steering gear clearance is carried out during the second maintenance. Loosening of the fastenings of the steering gear housing, steering column, steering wheel on the shaft, bipod is not allowed, and the steering linkages of passenger cars must be pinned and have no play. The amount of play in the steering wheel as a result of wear and loosening of parts, measured along the rim of the steering wheel, should not exceed the value established by the manufacturer. Malfunctions of hydraulic amplifiers are not allowed. Seizing of the steering mechanism (worm and roller) occurs when there is significant wear in the extreme positions, which are used less frequently during operation than the middle parts of the worm and roller. If there are hydraulic boosters, there is a need to periodically check the amount of pressure developed by the pump, which should be in the range of 60 - 70 kgf/cm2.

6 slide

Slide description:

Steering diagram 1 - steering wheel; 2 - steering shaft with a “worm”; 3 - “roller” with bipod shaft; 4 - steering bipod; 5 - average thrust; 6 - side rods; 7 - rotary levers; 8 - front wheels of the car; 9 - pendulum lever; 10 - steering rod joints

7 slide

Slide description:

The total play in the steering is the angle of rotation of the steering wheel from the position corresponding to the beginning of the steering wheels turning in one direction to the position corresponding to the beginning of their turning in the opposite direction. The total play in the steering under regulated test conditions should not exceed the limit values ​​​​established by the manufacturer in the operational documentation, and in the absence of such data should not exceed: 10° for passenger cars and units of trucks and buses created on their basis 20° for buses 25 ° for trucks The value of the total play in the steering is determined by the angle of rotation of the steering wheel between two fixed positions of the beginning of the turn of the steered wheels as a result of two or more measurements. The tension of the power steering pump drive belt and the level of working fluid in the reservoir must meet the requirements established by the vehicle manufacturer in the operating documentation.

8 slide

Slide description:

Slide 9

Slide description:

Assess the compliance of all steering elements with the vehicle structure. Assess the reliability of the steering wheel fastening to the steering column shaft. Check the functionality of the column position adjustment device (if equipped) and the reliability of its fixation in the specified positions. Assess the reliability of the steering column fastening. Assess the ease of rotation of the steering wheel over the entire range of rotation angles of the steered wheels, for which turn the steering wheel in the direction of travel and counterclockwise until it stops. After completing the check, return the steering wheel to the position corresponding to straight-line movement. On vehicles with hydraulic booster, determine the absence of spontaneous rotation of the steering wheel from the neutral position when the engine is running. Inspect the universal joints or elastic couplings of the steering column, assess the reliability of their fastening and make sure that there are no backlashes or wobbles in these connections not provided for by the design. Inspect the steering gear for damage and leakage of lubricating oil and working fluid. Assess the reliability of fastening the steering gear housing to the frame (body) by the presence of all fasteners and the absence of its mobility when the steering wheel is rotated in both directions. Inspect the steering gear parts for damage and deformation. Assess the reliability of fastening the parts to each other and to supporting surfaces. Check the presence of elements for fixing threaded connections.

10 slide

Slide description:

If there is a power steering system, check the level of working fluid in the pump reservoir with the engine running 12. If there is a belt drive of the power steering pump, inspect the drive belt for damage. Check for any movements of steering parts and assemblies not provided for by the design of the vehicle relative to each other or the supporting surface. 14. Inspect the devices that limit the maximum rotation of the steered wheels. make sure that the tires and wheel rims do not touch the body elements, chassis, pipelines and electrical harnesses in these positions. 15. Inspect the elements of the power steering system for leakage of working fluid. Make sure that the flexible hoses of the power steering system do not have cracks or damage reaching their reinforcement layer.

11 slide

Slide description:

Instruments for measuring total steering play When carrying out instrumental control, mechanical and electronic play meters are used.

12 slide

Slide description:

Mechanical play meter K-524 consists of: upper and lower sliding brackets, attached to the rim of the steering wheel with stops of a movable carriage, tightening the guide rods of the brackets using a clamp of a goniometric scale, installed on the axis of the clamp and having the ability to rotate by hand and self-braking (when the force is removed) for account of the friction rubber washer of a rubber thread, stretched using a suction cup from the clamp to the windshield of the car and playing the role of an “indicating arrow” of the goniometric scale of the loading device, which is a double-acting spring dynamometer

Slide 13

Slide description:

The method for measuring the total steering play performed by one operator is to identify the angle of rotation of the steering wheel on the angular scale of the play meter between two fixed positions, which are determined by applying equal forces to the load device alternately in both directions, regulated depending on the own weight of the vehicle axle, on the steered wheels. Table. Dependence of the force applied to the steering wheel rim on the vehicle weight attributable to the steered wheels Vehicle weight attributable to the steered wheels, t Loading device force, N (kgf) Up to 1.6 7.35(0.75) From 1.6 up to 3.86 9.80(1.00) Over 3.86 12.30(1.25) When turning the steered wheel, if a regulated force is applied to it, the fixed positions must correspond to the moment the wheel begins to turn, which is determined by the second operator visually or using additional means (for example, an indicator).

Slide 14

Slide description:

The ISL-401 electronic play meter is designed to measure the total steering play of cars, trucks, and buses by direct measurement of the angle of rotation of the steering wheel relative to the steered wheels. The main difference between the ISL-401 and K-524 play meter is the presence of a sensor that detects the beginning of wheel rotation, and not a dynamometer that measures the turning force. The operation of the device is based on measuring the total steering play by an angle sensor with a cutoff of the beginning and end of the reference according to the signals from the steering wheel start sensor. The device consists of two blocks: the main block and the wheel starting torque sensor